A proximity service (ProSe) refers to a service manner in which user equipments (UE) that are near each other transfer information to each other. The ProSe generally includes two processes: ProSe discovery and ProSe communication. The ProSe discovery refers to a process in which an adjacent UE is identified, and the ProSe communication refers to a process in which UEs that are near each other perform communication. The ProSe communication may be specifically classified into unicast communication, multicast communication, and the like. A ProSe may be described as a peer to peer (P2P) service, a device to device (D2D) service, or the like. In a ProSe system, there is a shorter distance and a shorter signal propagation path between a UE sending a ProSe signal (which includes a ProSe discovery signal and a ProSe communication signal) and a UE receiving the ProSe signal, and less signal fading occurs; therefore, communication between the UEs can be directly performed, that is, service data or a signal does not need to be forwarded by a base station. In this case, transmit power of a ProSe signal sent by the UE is generally less, which can therefore achieve an objective of saving power and reducing interference.
In the ProSe system, the UE sending a ProSe signal needs to determine a resource used to send a D2D service, and the UE receiving a ProSe signal needs to determine a resource used to receive a D2D service. In the prior art, a resource used to send a D2D service/receive a D2D service is selected from a pre-configured resource pool, and a UE can acquire the pre-configured resource pool only when the UE is in a connection state. Some UEs may have no requirement to communicate with a base station, and these UEs may enter an idle state. However, a UE in an idle state still has a requirement of receiving or sending a D2D service. How to configure a resource pool for a UE in an idle state is a problem to be resolved.